1. Field of the Invention
The present invention concerns a nickel electrode for use in an alkaline battery and an alkaline battery using such a nickel electrode.
2. Description of the Prior Art
Production processes for producing a nickel electrode for use in a nickel-cadmium battery known at present include a so-called sintering method wherein a finely porous substrate (80% porosity) prepared by sintering nickel powder is impregnated on a perforated steel sheet with a nickel salt under a reduced pressure and then the nickel salt is converted into nickel hydroxide in an aqueous alkaline solution, and a so-called pasting method wherein nickel hydroxide powder in a slurry form is loaded on a highly porous current collector (90.about.98% porosity) made of sintered, alkaline-proof metal fibers.
The former method was developed during World War II, and it has been improved for every particular portion upto now. However, no principal changes have been made and it requires repeating, over several cycles, a series of complicated loading steps, that is, solution impregnation alkaline soaking water rinsing and drying. Accordingly, it has a drawback of being expensive. Further, since the energy density is limited to about 400 mAh/cc due to the structural factor, it has become difficult to satisfy the market needs along with the reduction for the weight and size of portable electronic equipment which has been under rapid progress at present (requiring about 600 mAh/cc). The pasting method has been developed in recent years for simplifying the production steps from different points of view, such as for current collectors, active materials and additives. In addition, it can attain the high energy density substantially capable of coping with present market needs. However, since sintered, highly porous alkaline-proof metal fibers used for the current collector are expensive, it still involves the drawback that the product cost is high for which a substantial improvement is demanded.
For overcoming various problems in such production steps and cost, it has been demanded for an ultimate electrode like that existent lead electrodes using only the core metal for the substrate and many researchers have made various studies. However, the present technique still involves various problems and has not yet been put to practical use.
The present invention will be described together with the results of our previous studies reaching the invention referring to drawings.